Electric circuit breaker



March 1o, 1942 y fp. BARTLETT 2,275,885

ELECTRIC CIRCUIT BREAKER Filed Jan. 30, 1940 722 .Saa/'ce af Inventor: Percy Baartlett,

Patented Mar. 10, 1942 42,275,885 ELECTRIC CIRCUIT BREAKER Percy Bartlett, Springiield, Pa., assgnor to General Electric Company, a corporationv of New York Application January 30, 1940, Serial No. 316,329

1o claims. (ci. zoo-14s) My invention relates to electric circuit breakers and more particularly to circuit breakers of the fluid-operated fluid-blast type wherein the functions of interrupting the circuit and thereafter isolating the contacts so that the circuit is maintained in the open position are incorporated.

In circuit breakers of the fluid-blast type, it ha-s been discovered that current or arc interruption takes place under the most advantageous condi# tions when the arcing contacts are rapidly separated to a distance permitting the iiow of a blast of fluid transverselyof the arc and contacts. This cross blast of air or other fluid cooperating with a suitable baiiie structure causes rapid circuit interruption. However, in ordr to be su're that restriking of the arc does not occur, isolating or disconnecting contacts are usually provided in addition to the arcing contacts which are opened vafter the arc has beenextinguished but while the fluid blast is still being maintained. In order to obtain the proper relationship and 1sequential operation of the arcing and disconnecting contacts, separate actuating means for the two contacts have been provided which must be interlocked by complicated arrangements 'so as to insure consecutive operation and thereby necessitates a large initial expense, high maintenance \costs and large space requirement. It is anobject of my invention to provide a fluid-operated circuit breaker performing both an arc-interrupting anddisconnecting function in which only a singe pair of contacts is required but wherein the' disconnecting function is separate from and subl sequent to the are-interrupting function.` According to my invention, only one set of contacts is required for performing both functions andthe disconnecting function always occurs subsequent-v ly to thecircuit-interrupting.function without the need of an elaborate interlocking scheme,

such subsequent operation being positively assured by the fluid-operated control system included therewith.

The'disconnecting contacts used heretofore in circut breakers, in order to insure permanent opening of the circuit, required a considerable separation of the contacts and, consequently, a`

large -amount of space wasnecessary for operating theseccntacts. It is another object of my invention to provide an electric circuit breaker perfoiming both interrupting and disconnecting Yfunctions wherein wide separation of the disconnecting contacts is obtained with a minimum amount of space for the operating mechanism therefor. Hence, according to another aspect of my invention, I have provided a novel operating L mechanism wherein the separation between the contacts when performing the disconnecting function is suiliciently great for permanently opening the circuit and yet wherein the space required for the operating mechanism for obtaining this large separation of the contacts is considerably reduced.

By employing the cross-blast feature of arc extinction, a much more effective and eliici'ent use of the fluid blast is obtained and the interrupting capacity for th'e same size of circuit breaker is greatly increased. This cross-blast feature is disclosed and broadly claimed in a joint application of David C. Prince, WilliamKn Rankin, and Wilfred F. Skeats, Serial No. 303,126, filed November 6, 1939, and assigned to the same assignee as the present invention.

The retractable pin type of contact has been known for some time,'for example, it is disclosed in United States -Letters Patent No. 2,084,855 granted June 22, 1937, upon an application of Josef Biermanns. In fluid-operated circuit breakers employing the retractable pin type of contact, it is important that a positive full stroke of the pin contact is obtainedand that no stalling in some midposition occurs; Even though the air or other fluid pressure is sufficient for initially retracting the contact, if this air pressure rapidly decreases, it is conceivable that this retracting pin type contact might be stalled in some midposition. It is another object ,of my invention to provide a new and improved fluid-operated circuit breaker employing a retractable pin type contact wherein the spring return-.means is of the diminishing-or negative gradient type. Therefore, according to'a further aspect of my invention, I provide a spring device against which the retractable pin is forced during circuit-interrupting operation which has a diminishing vor negative gradient so that, in operation thereof, a possible 'diminishing air pressure will be opposed by ade- .Further objects and advantages of my inven-I tion will become apparent as the following descriptionv proceeds and the features of novelty which characterize my invention will be pointed with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawing in which Fig.41 is a schematic diagram representing an embodiment of my invention, while Figs. 2 and 3 illustrate modifications of the embodiment illustrated inFig. 1.

Referring now to the drawing, I have illustrated my invention as applied to a fluid-operated circuit breaker of the cross fluid blast type comprising contacts II and I2 which are relatively movable with respect to one another both as interrupting vcontacts and as disconnecting or isolating contacts, contact I2 being a "stationary contact during the interrupting operation While contact II is the more or less stationary Contact during the subsequent disconnecting operation. Contactv II is illustrated as being of the retractable pin type and operable by a fluid motor comprising a suitable piston I3 reciprocatingly mounted within insulating cylinder I4 which may be provided with a metallic antifriction liner, not shown, if desired. Piston I3 is connected to an opposing link toggle mechanism I5, the other end of which is connected to a metallic housing I6 tted against the end of cylinder I4. Metallic housing I6 is provided with openings or ports I1'and I8 through which air or other iiuid from cylinder I4 may escape when piston I3 movesupwardly to decrease the volume within cylinder I4 and metallic housing I6. l The cylinder I4 and metallic housing I6 are suitably supported in a container I9 on insulators 20. Openings I1 and I8 may be made adjustable by the provision of suitable valves or cocks to obtain any desired dashpot control for the moving piston I3. For example, in Fig. 2, I have illustrated port I8 as provided with an, adjustable lift nonreturn Valve I8a provided with openings I8 through which a predetermined leakage may take place. The lift of valve I8a may be adjusted by means I 8b. It will be understood by those skilled in the art that these adjustablelift nonreturn valves, such as I8a, may be used to pro long eitherthe pistons upward opening stroke or alternatively its downward return stroke,l dethe spring pressure gradually decreases as the contact reaches its open position. It may be d esirable to provide means for suitably balancing and adjusting springs 2| and, accordinglyyin Fig. 2, I have illustrated a plug I6' forthe end of metallic housing I6 by means of which the springs 2I may be suitably adjusted or balanced. It will, therefore, be evident to those skilled in the art that a correct balance and also proper timing for the disconnecting response may be obtained for optimum interrupting and disconnecting operations by suitably adjusting valve I8a, Fig. 2, and a similar valve I1a, not shown, with respect to the spring forces and the operating air pressures. Contact II is connected to the power line 22 through opposing link toggle mechanism I5 and metallic housing I6, although other means for carrying the current maybe utilized where the amperages are high, such, for example, as suitable ilexible connections or the use of a metallic liner for cylinder I4 as referred to above.

-I have illustrated my invention as applied to a circuit breaker of the cross-blast type and, ac-

pending upon which is originally selected. Inv the i into the circuit-closing position, I provide springs 2I which are mounted in housing I6 and one end oi these springs is connected to the pivot points of opposing link toggle mechanism I5. By this arrangement, the maximum component of spring pressure in a direction to force retractable pin contact II to the closed position occurs when retractable pin contact II is inthe circuit-closing position indicated in Fig. 1. As the contact II is moved upwardly by iluid or air pressure operating against the lower surface'of piston I3, .the component of spring force in the downward direction gradually decreases; inV other words. springs 2| are of the diminishing or negative gradient type in so 1far as retractable pin contact II is concerned so that, if the initial air pressure operating on piston I3 is suiiicient to start contact II retracting, it will more surely move contact II to the full open position with less hazard of stalling in some midposition sincey cordingly, the lower end of cylinder I4 is provided with a reduced opening or throat 23 which is adapted to be closed by contact I2 so that nfluid-cannot escape from throat 23 when contact I2 is in the closed position. Contact I2 is provided with an arcing tip I 2 of yarc resistant' metal and separation of contacts Il and I2 will cause' an arc to be drawn between the contacts I I and I2 in the lower end'of cylinder I4 adjacent the throat 23. Immediately after separation of the contacts, the arc is forced, by means of a blast of iluid or air from conduit 24,-into are chute 25 and the arc is driven against the edges of a plurality of partitions 26 in the arc chute', which partitions are transverse to tliearc gap. The arc chute -and cross-blast features just described are not my invention but are described and claimed in joint application Serial No. 303,126 referred to above.

Contact I2 which operates as a disconnecting contact subsequent to the operation of retractable pin contact II but prior to the interruption of the airV blast from conduit 24 is supported on plvotally mounted member 21 constructed of insulating material which is supported by shaft 23 rotatably mounted in abutment 29 attached to container or housing I9. Contact I2 is connected to power line 22 through conducting member 38 and links 3| and 32 forming a toggle plvotally connected to a support 33 mounted on an insulator 34 in the lower part of container or housing I9. When links 3I and 32 are in the collapsed position, shown dotted in Fig. 1, sufficient separation of contacts II and I2 is obtained for isolating purposes without requiring a great deal of space as would be necessary if a mechanism were provided vfor moving contact I2 vertically. It will be understood by those skilled in the art that links 3| and 32 may be replaced by any other suitable exible connection. A spring means 33 is provided between contact I2 and member 30 for providing the necessary wipe and, furthermore, for sealing purposes and cushioning the impact when contact I2 is moved against'throat 23. Contact I2 is operated as a disconnecting contact by means of crank 36 rigidly connected with plvotally mounted arm 21 of insulating mamounted at 39. The end of bell crank 33 connected to link 31 and, in turn, connected to crank 36 is so arranged that, in the closed position of the circuit breaker illustrated in Fig. 1, a toggle is formed preventing the blast of fluid through conduit 24 from forcing disconnecting or isolating contact I2 away from throat 23 at the lower end of cylinder I4. The provision of this toggle in the closed position of isolating contact I2 is well adaptedl for the pressure conditions in the circuit breaker; for, inasmuch as the pressure available for operating isolating contact'l2, as will be hereinafter described, undergoes a considerable reduction due to blast leakage, nevertheless, there is still ample pressure to apply the comparatively small upward force necessary for breaking the toggle 31-38 to initiate the disconnecting movement of isolating contact I2 and continue this movement to its completion. The other arm of bell ncrank 38 is associated with connecting rod 40 operated by piston 4I reciprocating .in cylinder 42.

The fluid or air under pressure for supplying the arc-extinguishing medium and also for operating the circuit breaker is obtained from a suitable source of fluid pressure, not shown, through conduit 43. Air or fluid under pressure from conduit 43 is transmitted to blast conduit 24. through blast valve 44, schematically shown, which-may be any of the conventional type of valves which permits a blast of air of predetermined duration to flow into pipe 24 when abnormal current conditions occur or when it is desired to manually operate the circuit breaker. Valve 44 may be similar to the valve disclosed and claimed in United States Letters Patent 1,912,024 granted May 30, 1933, upon an application of Werner Uebermuth, which valve may be arranged to respond electro-magnetically to abnormal current conditions.l However, any other suitable blast valve, such as a simple solenoid blast valve with a time delay device, may be provided for valve 44.

In order to operate disconnecting or isolating contact I2 subsequent to the interruption of the arc but prior to the interruption of the air blast from conduit 24, a port 45 is providedv in cylinder I4, which port, when piston I3 has been retracted sufficiently by fluid blast from conduit 24, is connected with the lower end of cylinder 42 by means of conduit 46. Thus when retractable pin contact I I has been retracted sufficiently, the fluid blast from conduit 24 is allowed to pass through conduit 46 through the lower end of cylinder 42', forcing piston 4I and connecting rod 40 upwardly whereby the toggle formed by bell crank 38 and link 31 is broken and disconnecting or isolating contact I2 is moved to the isolating position which is indicated by dotted lines in Fig. 1. Air or fluid on the upper side of piston 4I escapes to atmosphere through conduit 41, control valve 48 and conduit 49. As soon as the circuit has been effectively interrupted, blast valve 44 closes and retractable pin contact I I is forced to the circuit-closing position by springs 2|. In order to reclose the circuit breaker, however,`it'is necessary to operate valve 48, schematically shown, to interconnect the upper end of cylinder 42 with conduit 43 and, consequently,'with the fluid or air pressure source, whereby piston 4I is forced downwardly and, consequently, contact I2 is moved to the circuit-closing position sealing throat 23 to prevent the escape of fluid when the next circuit-interrupting operation occurs.

It lwill be understood'by those skilled in the Cil art that the circuit breaker described above may readily be modified to provide a blast of fluid during closing operation of the circuit breaker such as described and claimed in the above-mentioned co-pending application Serial No. 303,126. This blast, for example, may be of short duration and insuiiicient to overcome contact II or, on the other hand, it may be of longer duration so that momentarily retraction of contact II occurs just prior to the closing of isolating contact I2. In such a case, blast valve 44, if of the solenoid-operated type would be energized with an `electrical impulse just prior to the closing of the circuit breaker so that isolating contact I2 would be washed by a blast of cooling air passing through 'the throat 23. In case contact II is momentarily retracted during the closing operation of the circuit breaker even though port 45 would be uncovered, nevertheless, isolating contact I2 would be urged to its closed position by virtue of the full air pressure impressed on the upper side of piston 4I while only reduced pressure, due to the blast leakage, would operate against the under side of piston 4I. In fact, this reduced opposing force may be beneficial in providing a builing or dashpot action to decelerate the moving parts of the apparatus toward the termination of the closing stroke of isolating contact I2. v

The operation of the arrangement disclosed in Fig, 1 will be understood by those skilled in the art and, therefore, will only be briefly described hereinafter. Assuming that the circuit breaker is in the closed position indicated by solid lines in Fig. 1 and that an abnormal current condition occurs in power lines 22 and 22, blast valve 44 is operated to allow a blast of air or fluid of predetermined duration to flow through conduit 24. Since contact II substantially closes the entrance to arc chute 25, this blast of fluid perates against the lower side of piston I3, forci g retractable pin contact II away from contact I2 against the force of springs 2I acting on opposing link toggle mechanism I5. An arc is thereby drawn between contacts I'I and I2'which is forced against arc separators 26 by the fluid or air blast from conduit 24, whereby the arc is effectively interrupted. Isolating or disconnecting contact I2 is held against throat 23 in View of the toggle position of links 31 and one arm of bell crank 38. However, as soon as retractable pin contact II has moved upwardly a sufficient distance so that port 45 is uncovered to interconnect blast conduit 24 and conduit 46, air or uid under pressure is allowed to enter cylinder 42 and operate against the under side of piston 4I. Piston 4I operating on bell crank 38. through connecting rod 40 moves contact I2 to the isolating position shown in dotted lines in Fig. 1. By virtue of the toggle comprising links 3I and 32 and the operating mechanism for contact I2. a minimum amount of space is required while, at the same time, obtaining a wide separation of contacts Il and I2 for isolating purposes. As soon as the air or fluid blast of predetermined duration controlled by valve 44 has been interrupted, retractable pin contact II is forced downwardly by diminishing or negative gradient springs 2l Aso as to be ready for the next circuit-closing operation. During the opening operation of the circuit breaker, air or fluid above piston I3 is allowed to escape through openings I'I and I8 while air or fluid above piston 4I- is allowed to escape through conduit 41,

.rate of return of piston 55.

valve 48 which is open to atmosphere, and conduit 49;

If it should now be desired to close the circuit breaker, valve 48 is operated either manually or by other suitable -control means to interconnect the source of air or fluid pressure with the upper end of cylinder 42, whereby isolating contact l2 is moved into sealing engagement with throat 23 and into electrical contact with retractable pin contact Il.

Sometimes it is desirable to provide a circuit breaker having automatic reclosing features whereby the circuit is interrupted under abnormal current conditions but the circuit is immediately reclosed one or more times inl the hope that the abnormal condition has been removed and that service can be restored. Such reclosing features may be incorporated in the circuit breaker illustrated in Fig. 1 by providing a valve 50 of the .type schematically shown in Fig. 2 connected in conduit 48 of Fig. 1. A conduit 5| is provided for valve 50, which is connected to the source of fluid or air under pressure, not shown. Valve 50 includes a ball valve 52 spring biased to the closed position by means of springs 53.

rThe lift of ball valve 52 is adjusted by means of adjusting screw 54. A piston 55 is mounted within the housing of valve 50 and is biased to the position shown in Fig. 2 by means of spring 56. When piston 55 is moved downwardly by fluid pressure, an extension 51 thereof engages springbiased valve member 58 opening it to allow air or fluid to vflow through pipe 5I, valve 58, conduit 46', and conduit 46 to the lower end of cylinder 42 for operating the disconnecting vcontact I2. Valve 58 is double acting in that, at the time it allows -iluid from the .pressure source to pass from conduit 5I to conduit 46, it also closes a port 59 through which fluid below piston 4I is allowed to escape when the disconnecting contact'l2 is moved to the circuit-closing position. Valve 50 is so constructed that several successive blasts of air from port 45 are necessary to force piston 55 downwardly in a series of progressive steps to finally open valve 58. The extent of each downward impulse and, therefore, the number of reclosures of the breaker is adjusted by controlling the lift of the admission ball valve 52; This maybe adjusted, for example, by means of screw 54 so that the breaker will close three su-ccesstive times before disconnecting or isolating contact I2 is moved to the isolating position after which the breaker must be manually closed.

A needle valve is provided which controls the It will be understood by those skilled in the art that the automatic reclosing feature of my circuit breaker may be obtained by other than the pneumatic control just described. For example, an electrical control or a semielectrical and semipneumatic control might equally well be used.

For simplicity of illustration and description, I have disclosed my invention in connection with a single-phase circuit breaker but it will be understood that it is equally applicable to a polyphase circuit breaker in which case a plurality of pivotally mounted levers 21 of insulating material would be secured to a common shaft 28 and a single operating cylinder 42 would control al1 three levers 21. Furthermore, the blast valve 44 could be used to control the uid blast to all three breakers and, hence, conduit 24 would be connected to a common manifold with the corresponding conduits for the other phases.

. It will be apparent to those skilled 'in the art that my invention is not limited to the particular construction shown but that changes and modicatons may be made Without departing from the spirit and scope of my invention and I aim in the appended claims to cover al1 such changes and modifications.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric circuit breaker including a plurality of relatively movable coacting contacts associated with an arcing chamber, a source of fluid under pressure, means operable by said source ,of fluid for actuating one of said contacts, means for interconnecting said source of fluid with said arcing chamber to actuate said firstmentioned means and to provide a blast of fluid for arc-extinguishing purposes, and means for moving said other contact subsequent to and directly dependent upon a predetermined movement of said inst-mentioned contact for circuit isolating purposes.

2. In an electric circuit breaker, the combination comprising a plurality of relatively movable contacts associated with a chamber, a source of fluid under pressure, (means for connecting said source of fluid with said chamber, a piston located in said chamber operable by iluid pressure for moving one o f said contacts for circuitinterrupting purposes, means opposing the movement of said piston with a diminishing force as said one contact is moved for circuit interrup- 'tion, and means for moving another of said contacts subsequent to the operation of said rstmentioned means and the interruption of said circuit.

3. In an electric circuit breaker, the combination comprising a pair of relatively movable contacts associated with a chamber, a source of fluid under pressure, a piston reciprocatingly mounted in said chamber and operatively connected to one of said contacts, means for connecting said source of fluid with said chamber so as to'move said piston and connected contact for circuit-interrupting purposes, fluid-operated means for moving ,said other contact, and means for interconnecting said source of fluid pressure and said duid-operated means when said piston has reached a predetermined point in said chamber whereby said second contact is moved subsequent tothe movement of said first-mentioned contact for circuit-isolating purposes.

4. In an electric circuit breaker, the combina- 'tion comprising a pair of relatively movable coacting contacts, means for moving one of said contacts for circuit-interrupting purposes, said second contact being pivotally mounted so as to provide 'a wide contact separation while requir ing a'relatively-small space forI operation, and means for moving said second contact for circuitisolating purposes in direct dependence upon and after a predetermined movement of said one contact.

5. An electric circuit breaker comprising a pair of relatively movable contacts, a chamber having a restricted throat portion, one ofv said contacts being of the retractable pin type mounted for reti-action within said chamber, said second contact mounted so as to close said throat of said chamber during the closed circuit position of said circuit breaker, fluid pressure means for retracting said pin type contact to effect an interruption of said circuit,A means for preventing said second contact from moving away from said throat during said circuit-interrupting period, and means for moving said second contact for circuit-isolating purposes after said circuit has been interrupted.

6. In an electric circuit breaker, the combination comprising a pair of relatively movable con.. tacts associated with a'chamber, a source of fluid under pressure, a piston reciprocatingly mounted in said chamber and operatively connected to one of said contacts, means for connecting said source of fluid with said chamber so as to move said piston and connected contact for circuit-interrupting purposes, duid-operated means for moving said other Contact, and means for interconnecting said source of uid pressure and said fluid-operated means after a predetermined number of successive operations of said first-mentioned contact whereby said second contact is moved for circuit-isolating purposes after a predetermined numberof reclosures of said circuit breaker.

7. An electric circuit breaker comprising a pair of relatively movable contacts, a iiuid motor for operating one of said contacts, a source of fluid under pressure, means for connecting said source of fluid with said fluid motor so as to move one of said contacts for circuit-interrupting purposes, fluid-operated means for moving said other contact, means including a valve interconnecting said source and said uid-operated means, and means for progressively opening said valve with successive operations of said iiuid motor so that said other contact is operated for circuit-isolating purposes after a predetermined number of operations of said fluid motor.

8. An electric circuit breaker including a plurality of relatively movable contacts associated with an arcing chamber, a source of fluid under pressure, a fluid motor for actuating one-of said contacts, means for interconnecting said source of fluid with said fluid motor to actuate one of said contacts for circuit-interrupting purposes, adjustable means for controlling the operation of said uid motor including an adjustable valve, and means for moving said other contact subsequent to and dependentA upon the operation of said first-mentioned contact for 'circuit-isolating purposes.

9. In an electric circuit breaker including a pair of relatively movable coacting contacts, means for moving one of said contacts for circuitinterrupting purposes, and means directly dependent upon a predetermined movement -of said one contact for moving the other of said contacts for isolating purposes after the circuit has been interrupted.

10. In an electric circuit breaker including a pair of relatively movable contacts, uidoperated means connected to one of said contacts, a source of fluid under pressure, means connecting said source and said fluid-operated means so as to cause movement of said one contact for circuitinterrupting purposes, duid-operated means for moving said other contact, and means for interconnecting said source of fluid pressure and said last-mentioned duid-operated means after a pre'- determined number of successive operations of said first-mentioned contact whereby said second contact is moved for circuit isolatingpurposes 

